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Muslims and Christians may have been the groups he had in mind that day, but Bruneau, a child of California hippies who took an unusual route to Penn's Annenberg School for Communication, ultimately has broader goals in mind. What if there is a psychological key that could defuse the animosity between hate-filled groups around the globe? That includes U.S. Republicans and Democrats, who, his research has found, are almost as alienated from one another as Palestinians and Israelis. The only difference, he said, "is that we're not actually killing each other."

Most of us think the antidote to hate and close-mindedness is emotional. But, so far, Bruneau's research shows that the way to the mind is not necessarily through the heart. In fact, he believes, the way to the heart is through the mind.

Bruneau wanted to know more about what kind of arguments effectively combat common prejudices: that Muslims are terrorists, that they don't want to assimilate, that they are intolerant and hate American freedom. Liberals often believe that Muslim women are oppressed. He enlisted members of the Muslim Students Association to look for videos they thought might prove persuasive. He thought firsthand experience with discrimination might be helpful. (He's also working with former white nationalists.) He was looking, he told them, for "individualized psychological medicine."

At a recent meeting, two women suggested a video from the Secret Life of Muslims website that focused on Khalid Latif, who is now a chaplain at New York University and had previously worked for the New York City Police Department. He was young, good-looking, likable, and articulate. He had met the pope, the Dalai Lama, and former President Barack Obama. And he had faced depressing, maddening discrimination. Surely, they thought, any viewer could empathize with Latif's plight.

Bruneau understood the intuitive appeal, but, based on his research, he was skeptical. It would be too easy, he thought, to come up with the counter-arguments that are common in polarized groups. A few minutes of discomfort for Latif, anti-Muslim groups might argue, are a small price for greater safety for the rest of us.

"My intuition is it's going to be totally ineffective," Bruneau told the women.

Emily Falk, another Annenberg professor who has collaborated with Bruneau, said he is "unusual in the extent to which he is at the intersection of multiple different fields." Others are also passionate about making the world more peaceful, but few are doing his type of "clean, conclusive science." Many are doing science, but, nobody, she said, has the "same pulse on the real world."

Bruneau, now 44, was 29 before he started working on his doctorate in cellular and molecular neuroscience. In part, he wanted to understand his late mother, who had schizophrenia. A science lover, he taught elementary and high school kids after college. Vacations are what put him on his current path. He went to several countries torn by civil violence, including South Africa, Ireland, and Sri Lanka. While the people and cultures were very different, Bruneau noticed themes in how people felt about their enemies.

"I felt like you could take the words out of a Tamil villager's mouth and put them into the mouth of a young Catholic kid growing up in Belfast, and they would make complete sense," he said.

The underdog group said that it felt humiliated by the majority and that their oppressors saw them as lesser beings. The majority group dehumanized the others. They'd say such things as, "You can't negotiate with terrorists" or "They're inherently irrational." Bruneau was "amazed" that even people who were capable of great empathy for members of their own group "didn't necessarily express empathy for the other side." Feeling dehumanized made members of a group more likely to see their opponents as animals. A vicious cycle was born.

The neuroscientist in Bruneau thought of something that might explain these reactions to groups perceived as different and threatening. "I think what it is, is they all share a human brain," he said. He thought that if he could "find a key that gets people past one of these cognitive pitfalls ..., then it might be applied widely across many different conflicts."

Bruneau started using brain imaging and questionnaires to explore how enemies think and what kind of messages can change that. He started studying American politics because of its increasing polarization.

One quirk of human thinking that makes it hard to get through is "confirmation bias," the tendency to like information that supports a view we already hold and to give that information more credibility. When exposed to facts that support each side of an argument, Bruneau said, partisans on both sides often become more confident in their beliefs. People usually don't know they have this bias. The added problem now is that people can choose to live in a media bubble that rarely even tries to challenge their views. In addition, opposing groups often interpret the same facts very differently.

Dehumanization, he said, predicts attitudes and behaviors toward an opposing group in a wide variety of countries, including the United States, Hungary, Greece, the Netherlands, Israel, and Lebanon.

He measures it with a simple, if insulting, test. He shows study subjects the classic "ascent of man" picture. There's an ape on the left and a modern human on the right, with a few intermediate steps in between. He asks: Where would you put Muslims or some other group on this chart? If modern man is 100 on a scale of 0 to 100, both Republicans and Democrats put members of the other party 20 points lower than members of their own party. (Even people who don't believe in evolution get the idea.)

A recent study used the ascent of man illustration to look at dehumanization of Muslims by Americans. It was highest among supporters of Donald Trump, then a candidate for president. The research also found that Muslims who perceived that dehumanization was high were more inclined to support violent collective action and less likely to help in counterterrorism efforts.

Intuitively, we think that stories about likable or abused Muslims would change minds. Bruneau recently tested multiple videos for effectiveness, after first asking people to predict which would be best. They bet on emotional pitches. "There was zero correlation between predictions and reality," he said.

What worked best was a "very cerebral" video from Al Jazeera in which a Muslim woman said blaming all Muslims for terrorism was like blaming all Christians for the actions of Westboro Baptist Church or the KKK.

In this case, Bruneau suspects, American prejudices are "based on very little information." That makes them vulnerable to facts. "You can get to the heart from the head if the scaffold upon which people's biases are built is flimsy," he said. Changing minds about an issue such as abortion, he said, would be harder.

Bruneau has yet to find the key to opening human minds -- or hearts. He is testing messages and will soon try a social-media experiment. He will invite college Democrats and Republicans to a Facebook site where politics will be discussed, but snark and debate will be off-limits. He thinks those increase the tendency to focus on writing a witty retort instead of listening, and they freeze out people who feel intimidated and less informed. Participants will be encouraged to post political information. In exchange, they'll agree to read something from the other side. All will be asked to write about what they learned.

Should we be comforted by the fact that Americans are managing to live in separate political worlds without much violence? Bruneau isn't sure.

"The most pessimistic aspect of me," he said, "would say that, in a lot of conflicts in many different regions, Yugoslavia, Rwanda, Sri Lanka, that you had communities that were intermarrying and peaceful until they weren't, and then they really weren't."